Tach on my 1995 eldorado is not correct

You will need a computer to accurately read the signals you are getting from the sensors in the engine bay, but my guess is that the MAF sensor may be acting up.

Hi, You could have a vacuum leak. Check all hoses that are connected on or near the intake manifold and throttle body. Good luck.

The gas tank sounds like a bad ground usually located under the car at the gas tank. I do not know but maybe they both tach and fuel gague get their ground from the same place.

crank sensor is tied in with the tach. you have problem with crank sensor or electrical problem. the tach reads rpms, if the sensor is bad it throws the rpms way off. this is why you get the jumping in gauge.

The most likely problem is that you need a new voltage regulator put in the alternator,the tach runs off of it and when the tach quits i think you will find that the car also stops charging,the brushes for the alternator are in the regulator and a new one usually fixes the problem.

can be the cluster unit or ignition module that is at fault. clusters are exchanged units at any cadillac dealer. the ignition module sends the signal for the reading on the tach gauge

The serpentine belt is not the same as the timing belt! Not sure how your tach reads but at idle it will never be zero unless the car is not running. The tach tells the engine speed and if it is running you have to get some kind of reading. The idle may need adjusted or a vacuum line could be off but a zero reading at idle at a light is not correct.

A verry large Vacumn leak .. check for a hose off somewhere..particularily the PCV hose..also were the O rings present or missaligned on the Injectors?? also the gaskets between the lower and upper Intake manifolds could cause this if they were not installed in the proper position.. If you have a scan tool Check Idle air controll motor...Under data stream IAC will read 0 counts this will confirm a vacumn leak

you need to reprogram the tach as it may be a little stronger or weeker in your current van

Sounds like a problem in the cluster. These years of VW the clusters could be repared but by someone who knows what they are doing seeing it's printed boards.